• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 346 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS114S08: Why noise not decreased as date rate decreased in ADS114S08

? ?
Prodigy 10 points
Part Number: ADS114S08
Other Parts Discussed in Thread: ADS124S08

as mentioned in ADS114S08 datasheet, the increasing of OSR, will help to improve the noise performance of ADC

but in its datasheet noise value table, the noise rms and peak to peak value are not changed as OSR increase, please see below table

  • 0
    TI__Guru 63855 points

    Hello,

    The ADS114S08 (16-bit) has similar AFE performance as the ADS124S08 (24-bits) and so the noise of the ADC is dominated by the quantization noise of the ADC resolution, not the modulator/front-end noise and therefore the noise does not scale with data rates.  With a 5V reference, 5V/(2^24) = 76.29uV.  With a PGA G=128  -> 5V/(128V/V*(2^24)) = 0.596uV. 

  • 0 in reply to Collin Wells
    Prodigy 10 points

    hello,

    thanks for your answer,

    so you mean quantization noise is not impacted by the OSR?

    the 76.29uV is input referred noise ,right? then how to calculate output referred noise?

    thanks a lot

  • +1 in reply to ? ?
    TI__Guru 63855 points

    Hello,

    Yes, the quantization noise is based on the resolution of the ADC core, which is 16-bits and it is therefore not impacted by OSR.

    You'll multiply the input referred noise by the gain to get the output referred noise. With G=1 the input and output-referred noise values are equal.